Semiconductor device process technology nodes often employ isolation techniques to prevent current leakage between adjacent semiconductor devices and reduce parasitic capacitance. Two of these techniques include trench isolation and silicon-on-insulator (SOI) technology.
Trench isolation provides lateral isolation of two different types of transistors. For example, trench isolation may be used to separate an n-channel transistor's p-well structure from a p-channel transistor's n-well structure. Isolation trenches are created by etching a pattern of trenches in the silicon and then depositing one or more dielectric materials (e.g., silicon dioxide), which acts as an electric insulator, to fill the trenches.
SOI technology reduces parasitic capacitance due to isolation from the bulk silicon and provides resistance to latchup due to complete isolation of the n- and p-well structures. One typical SOI fabrication process includes growing a thick layer of dielectric material (e.g., silicon dioxide) on a handle wafer. A second wafer is then bonded on top of the grown dielectric material of the handle wafer. The second wafer is then placed through a grinding and polishing process to achieve semiconductor grade material that may be utilized to form semiconductor devices.